Merged revisions 80552-80556,80564-80566,80568-80571 via svnmerge from

svn+ssh://pythondev@svn.python.org/python/trunk

........
  r80552 | victor.stinner | 2010-04-27 23:46:03 +0200 (mar., 27 avril 2010) | 3 lines

  Issue #7449, part 1: fix test_support.py for Python compiled without thread
........
  r80553 | victor.stinner | 2010-04-27 23:47:01 +0200 (mar., 27 avril 2010) | 1 line

  Issue #7449, part 2: regrtest.py -j option requires thread support
........
  r80554 | victor.stinner | 2010-04-27 23:51:26 +0200 (mar., 27 avril 2010) | 9 lines

  Issue #7449 part 3, test_doctest: import trace module in test_coverage()

  Import trace module fail if the threading module is missing. test_coverage() is
  only used if test_doctest.py is used with the -c option. This commit allows to
  execute the test suite without thread support.

  Move "import trace" in test_coverage() and use
  test_support.import_module('trace').
........
  r80555 | victor.stinner | 2010-04-27 23:56:26 +0200 (mar., 27 avril 2010) | 6 lines

  Issue #7449, part 4: skip test_multiprocessing if thread support is disabled

  import threading after _multiprocessing to raise a more revelant error message:
  "No module named _multiprocessing". _multiprocessing is not compiled without
  thread support.
........
  r80556 | victor.stinner | 2010-04-28 00:01:24 +0200 (mer., 28 avril 2010) | 8 lines

  Issue #7449, part 5: split Test.test_open() of ctypes/test/test_errno.py

   * Split Test.test_open() in 2 functions: test_open() and test_thread_open()
   * Skip test_open() and test_thread_open() if we are unable to find the C
     library
   * Skip test_thread_open() if thread support is disabled
   * Use unittest.skipUnless(os.name == "nt", ...) on test_GetLastError()
........
  r80564 | victor.stinner | 2010-04-28 00:59:35 +0200 (mer., 28 avril 2010) | 4 lines

  Issue #7449, part 6: fix test_hashlib for missing threading module

  Move @test_support.reap_thread decorator from test_main() to test_threaded_hashing().
........
  r80565 | victor.stinner | 2010-04-28 01:01:29 +0200 (mer., 28 avril 2010) | 6 lines

  Issue #7449, part 7: simplify threading detection in test_capi

   * Skip TestPendingCalls if threading module is missing
   * Test if threading module is present or not, instead of test the presence of
     _testcapi._test_thread_state
........
  r80566 | victor.stinner | 2010-04-28 01:03:16 +0200 (mer., 28 avril 2010) | 4 lines

  Issue #7449, part 8: don't skip the whole test_asynchat if threading is missing

  TestFifo can be executed without the threading module
........
  r80568 | victor.stinner | 2010-04-28 01:14:58 +0200 (mer., 28 avril 2010) | 6 lines

  Issue #7449, part 9: fix test_xmlrpclib for missing threading module

   * Skip testcases using threads if threading module is missing
   * Use "http://" instead of URL in ServerProxyTestCase if threading is missing
     because URL is not set in this case
........
  r80569 | victor.stinner | 2010-04-28 01:33:58 +0200 (mer., 28 avril 2010) | 6 lines

  Partial revert of r80556 (Issue #7449, part 5, fix ctypes test)

  Rewrite r80556: the thread test have to be executed just after the test on
  libc_open() and so the test cannot be splitted in two functions (without
  duplicating code, and I don't want to duplicate code).
........
  r80570 | victor.stinner | 2010-04-28 01:51:16 +0200 (mer., 28 avril 2010) | 8 lines

  Issue #7449, part 10: test_cmd imports trace module using test_support.import_module()

  Use test_support.import_module() instead of import to raise a SkipTest
  exception if the import fail. Import trace fails if the threading module is
  missing.

  See also part 3: test_doctest: import trace module in test_coverage().
........
  r80571 | victor.stinner | 2010-04-28 01:55:59 +0200 (mer., 28 avril 2010) | 6 lines

  Issue #7449, last part (11): fix many tests if thread support is disabled

   * Use try/except ImportError or test_support.import_module() to import thread
     and threading modules
   * Add @unittest.skipUnless(threading, ...) to testcases using threads
........

33 files changed, 244 insertions, 147 deletions

diff --git a/Lib/test/fork_wait.py b/Lib/test/fork_wait.py
index 03a4d6f..533c0c2 100644
--- a/Lib/test/fork_wait.py
+++ b/Lib/test/fork_wait.py
@@ -1,6 +1,6 @@
 """This test case provides support for checking forking and wait behavior.
 
-To test different wait behavior, overrise the wait_impl method.
+To test different wait behavior, override the wait_impl method.
 
 We want fork1() semantics -- only the forking thread survives in the
 child after a fork().
@@ -9,7 +9,9 @@ On some systems (e.g. Solaris without posix threads) we find that all
 active threads survive in the child after a fork(); this is an error.
 """
 
-import os, sys, time, _thread, unittest
+import os, sys, time, unittest
+import test.support as support
+_thread = support.import_module('_thread')
 
 LONGSLEEP = 2
 SHORTSLEEP = 0.5
diff --git a/Lib/test/regrtest.py b/Lib/test/regrtest.py
index 41fc43b..c432ca4 100755
--- a/Lib/test/regrtest.py
+++ b/Lib/test/regrtest.py
@@ -515,7 +515,11 @@ def main(tests=None, testdir=None, verbose=0, quiet=False,
         tests = iter(selected)
 
     if use_mp:
-        from threading import Thread
+        try:
+            from threading import Thread
+        except ImportError:
+            print("Multiprocess option requires thread support")
+            sys.exit(2)
         from queue import Queue
         from subprocess import Popen, PIPE
         debug_output_pat = re.compile(r"\[\d+ refs\]$")
diff --git a/Lib/test/support.py b/Lib/test/support.py
index 9d39de8..4ea6c05 100644
--- a/Lib/test/support.py
+++ b/Lib/test/support.py
@@ -19,6 +19,10 @@ import collections
 import re
 import imp
 import time
+try:
+    import _thread
+except ImportError:
+    _thread = None
 
 __all__ = [
     "Error", "TestFailed", "ResourceDenied", "import_module",
@@ -1111,12 +1115,14 @@ def modules_cleanup(oldmodules):
 # at the end of a test run.
 
 def threading_setup():
-    import _thread
-    return _thread._count(),
+    if _thread:
+        return _thread._count(),
+    else:
+        return 1,
 
 def threading_cleanup(nb_threads):
-    import _thread
-
+    if not _thread:
+        return
     _MAX_COUNT = 10
     for count in range(_MAX_COUNT):
         n = _thread._count()
@@ -1126,6 +1132,13 @@ def threading_cleanup(nb_threads):
     # XXX print a warning in case of failure?
 
 def reap_threads(func):
+    """Use this function when threads are being used.  This will
+    ensure that the threads are cleaned up even when the test fails.
+    If threading is unavailable this function does nothing.
+    """
+    if not _thread:
+        return func
+
     @functools.wraps(func)
     def decorator(*args):
         key = threading_setup()
diff --git a/Lib/test/test_asynchat.py b/Lib/test/test_asynchat.py
index c743d6b..c79fe6f 100644
--- a/Lib/test/test_asynchat.py
+++ b/Lib/test/test_asynchat.py
@@ -5,96 +5,101 @@ from test import support
 # If this fails, the test will be skipped.
 thread = support.import_module('_thread')
 
-import asyncore, asynchat, socket, threading, time
+import asyncore, asynchat, socket, time
 import unittest
 import sys
+try:
+    import threading
+except ImportError:
+    threading = None
 
 HOST = support.HOST
 SERVER_QUIT = b'QUIT\n'
 
-class echo_server(threading.Thread):
-    # parameter to determine the number of bytes passed back to the
-    # client each send
-    chunk_size = 1
-
-    def __init__(self, event):
-        threading.Thread.__init__(self)
-        self.event = event
-        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
-        self.port = support.bind_port(self.sock)
-        # This will be set if the client wants us to wait before echoing data
-        # back.
-        self.start_resend_event = None
-
-    def run(self):
-        self.sock.listen(1)
-        self.event.set()
-        conn, client = self.sock.accept()
-        self.buffer = b""
-        # collect data until quit message is seen
-        while SERVER_QUIT not in self.buffer:
-            data = conn.recv(1)
-            if not data:
-                break
-            self.buffer = self.buffer + data
-
-        # remove the SERVER_QUIT message
-        self.buffer = self.buffer.replace(SERVER_QUIT, b'')
-
-        if self.start_resend_event:
-            self.start_resend_event.wait()
-
-        # re-send entire set of collected data
-        try:
-            # this may fail on some tests, such as test_close_when_done, since
-            # the client closes the channel when it's done sending
-            while self.buffer:
-                n = conn.send(self.buffer[:self.chunk_size])
-                time.sleep(0.001)
-                self.buffer = self.buffer[n:]
-        except:
-            pass
-
-        conn.close()
-        self.sock.close()
-
-class echo_client(asynchat.async_chat):
-
-    def __init__(self, terminator, server_port):
-        asynchat.async_chat.__init__(self)
-        self.contents = []
-        self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
-        self.connect((HOST, server_port))
-        self.set_terminator(terminator)
-        self.buffer = b""
-
-    def handle_connect(self):
-        pass
-
-    if sys.platform == 'darwin':
-        # select.poll returns a select.POLLHUP at the end of the tests
-        # on darwin, so just ignore it
-        def handle_expt(self):
-            pass
-
-    def collect_incoming_data(self, data):
-        self.buffer += data
-
-    def found_terminator(self):
-        self.contents.append(self.buffer)
-        self.buffer = b""
-
-
-def start_echo_server():
-    event = threading.Event()
-    s = echo_server(event)
-    s.start()
-    event.wait()
-    event.clear()
-    time.sleep(0.01) # Give server time to start accepting.
-    return s, event
+if threading:
+    class echo_server(threading.Thread):
+        # parameter to determine the number of bytes passed back to the
+        # client each send
+        chunk_size = 1
+
+        def __init__(self, event):
+            threading.Thread.__init__(self)
+            self.event = event
+            self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.port = support.bind_port(self.sock)
+            # This will be set if the client wants us to wait before echoing data
+            # back.
+            self.start_resend_event = None
+
+        def run(self):
+            self.sock.listen(1)
+            self.event.set()
+            conn, client = self.sock.accept()
+            self.buffer = b""
+            # collect data until quit message is seen
+            while SERVER_QUIT not in self.buffer:
+                data = conn.recv(1)
+                if not data:
+                    break
+                self.buffer = self.buffer + data
+
+            # remove the SERVER_QUIT message
+            self.buffer = self.buffer.replace(SERVER_QUIT, b'')
+
+            if self.start_resend_event:
+                self.start_resend_event.wait()
+
+            # re-send entire set of collected data
+            try:
+                # this may fail on some tests, such as test_close_when_done, since
+                # the client closes the channel when it's done sending
+                while self.buffer:
+                    n = conn.send(self.buffer[:self.chunk_size])
+                    time.sleep(0.001)
+                    self.buffer = self.buffer[n:]
+            except:
+                pass
+
+            conn.close()
+            self.sock.close()
+
+    class echo_client(asynchat.async_chat):
+
+        def __init__(self, terminator, server_port):
+            asynchat.async_chat.__init__(self)
+            self.contents = []
+            self.create_socket(socket.AF_INET, socket.SOCK_STREAM)
+            self.connect((HOST, server_port))
+            self.set_terminator(terminator)
+            self.buffer = b""
+
+            def handle_connect(self):
+                pass
+
+            if sys.platform == 'darwin':
+                # select.poll returns a select.POLLHUP at the end of the tests
+                # on darwin, so just ignore it
+                def handle_expt(self):
+                    pass
+
+        def collect_incoming_data(self, data):
+            self.buffer += data
+
+        def found_terminator(self):
+            self.contents.append(self.buffer)
+            self.buffer = b""
+
+    def start_echo_server():
+        event = threading.Event()
+        s = echo_server(event)
+        s.start()
+        event.wait()
+        event.clear()
+        time.sleep(0.01) # Give server time to start accepting.
+        return s, event
 
 
+@unittest.skipUnless(threading, 'Threading required for this test.')
 class TestAsynchat(unittest.TestCase):
     usepoll = False
 
diff --git a/Lib/test/test_asyncore.py b/Lib/test/test_asyncore.py
index 98a0819..ad4153c 100644
--- a/Lib/test/test_asyncore.py
+++ b/Lib/test/test_asyncore.py
@@ -3,7 +3,6 @@ import unittest
 import select
 import os
 import socket
-import threading
 import sys
 import time
 
@@ -12,6 +11,11 @@ from test.support import TESTFN, run_unittest, unlink
 from io import BytesIO
 from io import StringIO
 
+try:
+    import threading
+except ImportError:
+    threading = None
+
 HOST = support.HOST
 
 class dummysocket:
@@ -320,6 +324,7 @@ class DispatcherWithSendTests(unittest.TestCase):
     def tearDown(self):
         asyncore.close_all()
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
     @support.reap_threads
     def test_send(self):
         evt = threading.Event()
diff --git a/Lib/test/test_bz2.py b/Lib/test/test_bz2.py
index dbbdad3..63b3009 100644
--- a/Lib/test/test_bz2.py
+++ b/Lib/test/test_bz2.py
@@ -7,11 +7,14 @@ from io import BytesIO
 import os
 import subprocess
 import sys
-import threading
+
+try:
+    import threading
+except ImportError:
+    threading = None
 
 # Skip tests if the bz2 module doesn't exist.
 bz2 = support.import_module('bz2')
-
 from bz2 import BZ2File, BZ2Compressor, BZ2Decompressor
 
 has_cmdline_bunzip2 = sys.platform not in ("win32", "os2emx")
@@ -283,6 +286,7 @@ class BZ2FileTest(BaseTest):
         else:
             self.fail("1/0 didn't raise an exception")
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
     def testThreading(self):
         # Using a BZ2File from several threads doesn't deadlock (issue #7205).
         data = b"1" * 2**20
diff --git a/Lib/test/test_capi.py b/Lib/test/test_capi.py
index 0460679..29f7a71 100644
--- a/Lib/test/test_capi.py
+++ b/Lib/test/test_capi.py
@@ -6,8 +6,11 @@ import sys
 import time
 import random
 import unittest
-import threading
 from test import support
+try:
+    import threading
+except ImportError:
+    threading = None
 import _testcapi
 
 
@@ -33,6 +36,7 @@ class CAPITest(unittest.TestCase):
         self.assertRaises(AttributeError, setattr, inst.testfunction, "attribute", "test")
 
 
+@unittest.skipUnless(threading, 'Threading required for this test.')
 class TestPendingCalls(unittest.TestCase):
 
     def pendingcalls_submit(self, l, n):
@@ -148,17 +152,10 @@ def test_main():
             raise support.TestFailed(
                         "Couldn't find main thread correctly in the list")
 
-    try:
-        _testcapi._test_thread_state
-        have_thread_state = True
-    except AttributeError:
-        have_thread_state = False
-
-    if have_thread_state:
+    if threading:
         import _thread
         import time
         TestThreadState()
-        import threading
         t = threading.Thread(target=TestThreadState)
         t.start()
         t.join()
diff --git a/Lib/test/test_cmd.py b/Lib/test/test_cmd.py
index 11602f1..b3ad5d0 100644
--- a/Lib/test/test_cmd.py
+++ b/Lib/test/test_cmd.py
@@ -7,9 +7,9 @@ Original by Michael Schneider
 
 import cmd
 import sys
-import trace
 import re
 from io import StringIO
+from test import support
 
 class samplecmdclass(cmd.Cmd):
     """
@@ -169,11 +169,11 @@ class samplecmdclass(cmd.Cmd):
         return True
 
 def test_main(verbose=None):
-    from test import support, test_cmd
+    from test import test_cmd
     support.run_doctest(test_cmd, verbose)
 
 def test_coverage(coverdir):
-    import trace
+    trace = support.import_module('trace')
     tracer=trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix,],
                         trace=0, count=1)
     tracer.run('reload(cmd);test_main()')
diff --git a/Lib/test/test_contextlib.py b/Lib/test/test_contextlib.py
index c733bca..389e7d6 100644
--- a/Lib/test/test_contextlib.py
+++ b/Lib/test/test_contextlib.py
@@ -3,9 +3,12 @@
 import sys
 import tempfile
 import unittest
-import threading
 from contextlib import *  # Tests __all__
 from test import support
+try:
+    import threading
+except ImportError:
+    threading = None
 
 
 class ContextManagerTestCase(unittest.TestCase):
@@ -151,6 +154,7 @@ class FileContextTestCase(unittest.TestCase):
         finally:
             support.unlink(tfn)
 
+@unittest.skipUnless(threading, 'Threading required for this test.')
 class LockContextTestCase(unittest.TestCase):
 
     def boilerPlate(self, lock, locked):
diff --git a/Lib/test/test_doctest.py b/Lib/test/test_doctest.py
index 3616026..fc5153f 100644
--- a/Lib/test/test_doctest.py
+++ b/Lib/test/test_doctest.py
@@ -2341,8 +2341,10 @@ def test_main():
     from test import test_doctest
     support.run_doctest(test_doctest, verbosity=True)
 
-import trace, sys, re, io
+import sys, re, io
+
 def test_coverage(coverdir):
+    trace = support.import_module('trace')
     tracer = trace.Trace(ignoredirs=[sys.prefix, sys.exec_prefix,],
                          trace=0, count=1)
     tracer.run('test_main()')
diff --git a/Lib/test/test_docxmlrpc.py b/Lib/test/test_docxmlrpc.py
index 112be46..60a69dd 100644
--- a/Lib/test/test_docxmlrpc.py
+++ b/Lib/test/test_docxmlrpc.py
@@ -2,7 +2,7 @@ from xmlrpc.server import DocXMLRPCServer
 import http.client
 import sys
 from test import support
-import threading
+threading = support.import_module('threading')
 import time
 import socket
 import unittest
diff --git a/Lib/test/test_fork1.py b/Lib/test/test_fork1.py
index 74cd0c0..bf7fdcd 100644
--- a/Lib/test/test_fork1.py
+++ b/Lib/test/test_fork1.py
@@ -6,10 +6,10 @@ import os
 import signal
 import sys
 import time
-import threading
 
 from test.fork_wait import ForkWait
-from test.support import run_unittest, reap_children, get_attribute
+from test.support import run_unittest, reap_children, get_attribute, import_module
+threading = import_module('threading')
 
 # Skip test if fork does not exist.
 get_attribute(os, 'fork')
diff --git a/Lib/test/test_ftplib.py b/Lib/test/test_ftplib.py
index ab03faf..4e80dae 100644
--- a/Lib/test/test_ftplib.py
+++ b/Lib/test/test_ftplib.py
@@ -4,7 +4,6 @@
 # environment
 
 import ftplib
-import threading
 import asyncore
 import asynchat
 import socket
@@ -19,6 +18,7 @@ except ImportError:
 from unittest import TestCase
 from test import support
 from test.support import HOST
+threading = support.import_module('threading')
 
 # the dummy data returned by server over the data channel when
 # RETR, LIST and NLST commands are issued
diff --git a/Lib/test/test_hashlib.py b/Lib/test/test_hashlib.py
index 44eed78..4fb693e 100644
--- a/Lib/test/test_hashlib.py
+++ b/Lib/test/test_hashlib.py
@@ -311,10 +311,9 @@ class HashLibTestCase(unittest.TestCase):
         m = hashlib.md5(b'x' * gil_minsize)
         self.assertEquals(m.hexdigest(), 'cfb767f225d58469c5de3632a8803958')
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
+    @support.reap_threads
     def test_threaded_hashing(self):
-        if not threading:
-            raise unittest.SkipTest('No threading module.')
-
         # Updating the same hash object from several threads at once
         # using data chunk sizes containing the same byte sequences.
         #
@@ -349,7 +348,6 @@ class HashLibTestCase(unittest.TestCase):
 
         self.assertEqual(expected_hash, hasher.hexdigest())
 
-@support.reap_threads
 def test_main():
     support.run_unittest(HashLibTestCase)
 
diff --git a/Lib/test/test_httpservers.py b/Lib/test/test_httpservers.py
index 5aa4af4..6a93800 100644
--- a/Lib/test/test_httpservers.py
+++ b/Lib/test/test_httpservers.py
@@ -15,10 +15,10 @@ import shutil
 import urllib.parse
 import http.client
 import tempfile
-import threading
 
 import unittest
 from test import support
+threading = support.import_module('threading')
 
 class NoLogRequestHandler:
     def log_message(self, *args):
diff --git a/Lib/test/test_io.py b/Lib/test/test_io.py
index d5a6a4f..fa96f9a 100644
--- a/Lib/test/test_io.py
+++ b/Lib/test/test_io.py
@@ -23,7 +23,6 @@ import os
 import sys
 import time
 import array
-import threading
 import random
 import unittest
 import weakref
@@ -35,6 +34,10 @@ from test import support
 import codecs
 import io  # C implementation of io
 import _pyio as pyio # Python implementation of io
+try:
+    import threading
+except ImportError:
+    threading = None
 
 
 def _default_chunk_size():
@@ -742,6 +745,7 @@ class BufferedReaderTest(unittest.TestCase, CommonBufferedTests):
 
         self.assertEquals(b"abcdefg", bufio.read())
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
     def test_threads(self):
         try:
             # Write out many bytes with exactly the same number of 0's,
@@ -988,6 +992,7 @@ class BufferedWriterTest(unittest.TestCase, CommonBufferedTests):
         with self.open(support.TESTFN, "rb", buffering=0) as f:
             self.assertEqual(f.read(), b"abc")
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
     def test_threads(self):
         try:
             # Write out many bytes from many threads and test they were
@@ -2080,7 +2085,7 @@ class TextIOWrapperTest(unittest.TestCase):
         with self.open(support.TESTFN, "w", errors="replace") as f:
             self.assertEqual(f.errors, "replace")
 
-
+    @unittest.skipUnless(threading, 'Threading required for this test.')
     def test_threads_write(self):
         # Issue6750: concurrent writes could duplicate data
         event = threading.Event()
diff --git a/Lib/test/test_logging.py b/Lib/test/test_logging.py
index cec3ffe..c884d3e 100644
--- a/Lib/test/test_logging.py
+++ b/Lib/test/test_logging.py
@@ -41,10 +41,13 @@ import tempfile
 from test.support import captured_stdout, run_with_locale, run_unittest,\
      find_unused_port
 import textwrap
-import threading
 import unittest
 import warnings
 import weakref
+try:
+    import threading
+except ImportError:
+    threading = None
 
 
 class BaseTest(unittest.TestCase):
@@ -765,6 +768,7 @@ class LogRecordSocketReceiver(ThreadingTCPServer):
         self.server_close()
 
 
+@unittest.skipUnless(threading, 'Threading required for this test.')
 class SocketHandlerTest(BaseTest):
 
     """Test for SocketHandler objects."""
@@ -1659,6 +1663,7 @@ class ConfigDictTest(BaseTest):
     def test_config13_failure(self):
         self.assertRaises(Exception, self.apply_config, self.config13)
 
+    @unittest.skipUnless(threading, 'listen() needs threading to work')
     def setup_via_listener(self, text):
         text = text.encode("utf-8")
         port = find_unused_port()
diff --git a/Lib/test/test_multiprocessing.py b/Lib/test/test_multiprocessing.py
index 6d12d12..f9d02ed 100644
--- a/Lib/test/test_multiprocessing.py
+++ b/Lib/test/test_multiprocessing.py
@@ -5,7 +5,6 @@
 #
 
 import unittest
-import threading
 import queue as pyqueue
 import time
 import io
@@ -25,6 +24,10 @@ import test.support
 _multiprocessing = test.support.import_module('_multiprocessing')
 # Skip tests if sem_open implementation is broken.
 test.support.import_module('multiprocessing.synchronize')
+# import threading after _multiprocessing to raise a more revelant error
+# message: "No module named _multiprocessing". _multiprocessing is not compiled
+# without thread support.
+import threading
 
 import multiprocessing.dummy
 import multiprocessing.connection
diff --git a/Lib/test/test_poplib.py b/Lib/test/test_poplib.py
index aa703c5..c831fb4 100644
--- a/Lib/test/test_poplib.py
+++ b/Lib/test/test_poplib.py
@@ -4,7 +4,6 @@
 # a real test suite
 
 import poplib
-import threading
 import asyncore
 import asynchat
 import socket
@@ -14,6 +13,7 @@ import errno
 
 from unittest import TestCase
 from test import support as test_support
+threading = test_support.import_module('threading')
 
 HOST = test_support.HOST
 PORT = 0
diff --git a/Lib/test/test_queue.py b/Lib/test/test_queue.py
index 6ee78dd..3153829 100644
--- a/Lib/test/test_queue.py
+++ b/Lib/test/test_queue.py
@@ -1,10 +1,10 @@
 # Some simple queue module tests, plus some failure conditions
 # to ensure the Queue locks remain stable.
 import queue
-import threading
 import time
 import unittest
 from test import support
+threading = support.import_module('threading')
 
 QUEUE_SIZE = 5
 
diff --git a/Lib/test/test_smtplib.py b/Lib/test/test_smtplib.py
index 32d2d9b..d36ab0e 100644
--- a/Lib/test/test_smtplib.py
+++ b/Lib/test/test_smtplib.py
@@ -1,7 +1,6 @@
 import asyncore
 import email.utils
 import socket
-import threading
 import smtpd
 import smtplib
 import io
@@ -9,9 +8,14 @@ import sys
 import time
 import select
 
-from unittest import TestCase
+import unittest
 from test import support
 
+try:
+    import threading
+except ImportError:
+    threading = None
+
 HOST = support.HOST
 
 if sys.platform == 'darwin':
@@ -44,7 +48,8 @@ def server(evt, buf, serv):
         serv.close()
         evt.set()
 
-class GeneralTests(TestCase):
+@unittest.skipUnless(threading, 'Threading required for this test.')
+class GeneralTests(unittest.TestCase):
 
     def setUp(self):
         self._threads = support.threading_setup()
@@ -146,7 +151,8 @@ MSG_END = '------------ END MESSAGE ------------\n'
 # test server times out, causing the test to fail.
 
 # Test behavior of smtpd.DebuggingServer
-class DebuggingServerTests(TestCase):
+@unittest.skipUnless(threading, 'Threading required for this test.')
+class DebuggingServerTests(unittest.TestCase):
 
     def setUp(self):
         # temporarily replace sys.stdout to capture DebuggingServer output
@@ -241,7 +247,7 @@ class DebuggingServerTests(TestCase):
         self.assertEqual(self.output.getvalue(), mexpect)
 
 
-class NonConnectingTests(TestCase):
+class NonConnectingTests(unittest.TestCase):
 
     def testNotConnected(self):
         # Test various operations on an unconnected SMTP object that
@@ -262,7 +268,8 @@ class NonConnectingTests(TestCase):
 
 
 # test response of client to a non-successful HELO message
-class BadHELOServerTests(TestCase):
+@unittest.skipUnless(threading, 'Threading required for this test.')
+class BadHELOServerTests(unittest.TestCase):
 
     def setUp(self):
         self.old_stdout = sys.stdout
@@ -386,7 +393,8 @@ class SimSMTPServer(smtpd.SMTPServer):
 
 # Test various SMTP & ESMTP commands/behaviors that require a simulated server
 # (i.e., something with more features than DebuggingServer)
-class SMTPSimTests(TestCase):
+@unittest.skipUnless(threading, 'Threading required for this test.')
+class SMTPSimTests(unittest.TestCase):
 
     def setUp(self):
         self._threads = support.threading_setup()
diff --git a/Lib/test/test_socket.py b/Lib/test/test_socket.py
index 1e1e453..76d870b 100644
--- a/Lib/test/test_socket.py
+++ b/Lib/test/test_socket.py
@@ -7,8 +7,6 @@ import errno
 import io
 import socket
 import select
-import _thread as thread
-import threading
 import time
 import traceback
 import queue
@@ -21,6 +19,13 @@ import signal
 HOST = support.HOST
 MSG = b'Michael Gilfix was here\n'
 
+try:
+    import _thread as thread
+    import threading
+except ImportError:
+    thread = None
+    threading = None
+
 class SocketTCPTest(unittest.TestCase):
 
     def setUp(self):
@@ -560,6 +565,7 @@ class GeneralModuleTests(unittest.TestCase):
         s.ioctl(socket.SIO_KEEPALIVE_VALS, (1, 100, 100))
 
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class BasicTCPTest(SocketConnectedTest):
 
     def __init__(self, methodName='runTest'):
@@ -649,6 +655,7 @@ class BasicTCPTest(SocketConnectedTest):
         self.serv_conn.send(MSG)
         self.serv_conn.shutdown(2)
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class BasicUDPTest(ThreadedUDPSocketTest):
 
     def __init__(self, methodName='runTest'):
@@ -677,6 +684,7 @@ class BasicUDPTest(ThreadedUDPSocketTest):
     def _testRecvFromNegative(self):
         self.cli.sendto(MSG, 0, (HOST, self.port))
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class TCPCloserTest(ThreadedTCPSocketTest):
 
     def testClose(self):
@@ -696,6 +704,7 @@ class TCPCloserTest(ThreadedTCPSocketTest):
         self.cli.connect((HOST, self.port))
         time.sleep(1.0)
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class BasicSocketPairTest(SocketPairTest):
 
     def __init__(self, methodName='runTest'):
@@ -715,6 +724,7 @@ class BasicSocketPairTest(SocketPairTest):
         msg = self.cli.recv(1024)
         self.assertEqual(msg, MSG)
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class NonBlockingTCPTests(ThreadedTCPSocketTest):
 
     def __init__(self, methodName='runTest'):
@@ -783,6 +793,7 @@ class NonBlockingTCPTests(ThreadedTCPSocketTest):
         time.sleep(0.1)
         self.cli.send(MSG)
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class FileObjectClassTestCase(SocketConnectedTest):
     """Unit tests for the object returned by socket.makefile()
 
@@ -1098,6 +1109,7 @@ class NetworkConnectionNoServer(unittest.TestCase):
             lambda: socket.create_connection((HOST, port))
         )
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class NetworkConnectionAttributesTest(SocketTCPTest, ThreadableTest):
 
     def __init__(self, methodName='runTest'):
@@ -1160,6 +1172,7 @@ class NetworkConnectionAttributesTest(SocketTCPTest, ThreadableTest):
         self.cli = socket.create_connection((HOST, self.port), 30)
         self.assertEqual(self.cli.gettimeout(), 30)
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class NetworkConnectionBehaviourTest(SocketTCPTest, ThreadableTest):
 
     def __init__(self, methodName='runTest'):
@@ -1305,6 +1318,7 @@ class TestLinuxAbstractNamespace(unittest.TestCase):
         self.assertRaises(socket.error, s.bind, address)
 
 
+@unittest.skipUnless(thread, 'Threading required for this test.')
 class BufferIOTest(SocketConnectedTest):
     """
     Test the buffer versions of socket.recv() and socket.send().
diff --git a/Lib/test/test_socketserver.py b/Lib/test/test_socketserver.py
index 9578489..eb72528 100644
--- a/Lib/test/test_socketserver.py
+++ b/Lib/test/test_socketserver.py
@@ -9,12 +9,15 @@ import select
 import signal
 import socket
 import tempfile
-import threading
 import unittest
 import socketserver
 
 import test.support
 from test.support import reap_children, reap_threads, verbose
+try:
+    import threading
+except ImportError:
+    threading = None
 
 test.support.requires("network")
 
@@ -119,6 +122,7 @@ class SocketServerTest(unittest.TestCase):
         self.assertEquals(server.server_address, server.socket.getsockname())
         return server
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
     @reap_threads
     def run_server(self, svrcls, hdlrbase, testfunc):
         server = self.make_server(self.pickaddr(svrcls.address_family),
diff --git a/Lib/test/test_sys.py b/Lib/test/test_sys.py
index 1b21f50..a9f3f5e 100644
--- a/Lib/test/test_sys.py
+++ b/Lib/test/test_sys.py
@@ -11,6 +11,10 @@ import operator
 # strings to intern in test_intern()
 numruns = 0
 
+try:
+    import threading
+except ImportError:
+    threading = None
 
 class SysModuleTest(unittest.TestCase):
 
@@ -158,6 +162,7 @@ class SysModuleTest(unittest.TestCase):
                 sys.setcheckinterval(n)
                 self.assertEquals(sys.getcheckinterval(), n)
 
+    @unittest.skipUnless(threading, 'Threading required for this test.')
     def test_switchinterval(self):
         self.assertRaises(TypeError, sys.setswitchinterval)
         self.assertRaises(TypeError, sys.setswitchinterval, "a")
diff --git a/Lib/test/test_telnetlib.py b/Lib/test/test_telnetlib.py
index 4cb013e..6d7b6a6 100644
--- a/Lib/test/test_telnetlib.py
+++ b/Lib/test/test_telnetlib.py
@@ -1,12 +1,12 @@
 import socket
 import select
-import threading
 import telnetlib
 import time
 import contextlib
 
 from unittest import TestCase
 from test import support
+threading = support.import_module('threading')
 
 HOST = support.HOST
 
diff --git a/Lib/test/test_thread.py b/Lib/test/test_thread.py
index bac485f..894a493 100644
--- a/Lib/test/test_thread.py
+++ b/Lib/test/test_thread.py
@@ -2,7 +2,7 @@ import os
 import unittest
 import random
 from test import support
-import _thread as thread
+thread = support.import_module('_thread')
 import time
 import sys
 import weakref
diff --git a/Lib/test/test_threaded_import.py b/Lib/test/test_threaded_import.py
index 29eab1a..363aa0f 100644
--- a/Lib/test/test_threaded_import.py
+++ b/Lib/test/test_threaded_import.py
@@ -5,9 +5,9 @@
 # complains several times about module random having no attribute
 # randrange, and then Python hangs.
 
-import _thread as thread
 import unittest
-from test.support import verbose, TestFailed
+from test.support import verbose, TestFailed, import_module
+thread = import_module('_thread')
 
 critical_section = thread.allocate_lock()
 done = thread.allocate_lock()
diff --git a/Lib/test/test_threadedtempfile.py b/Lib/test/test_threadedtempfile.py
index 6d84e7e..6386b55 100644
--- a/Lib/test/test_threadedtempfile.py
+++ b/Lib/test/test_threadedtempfile.py
@@ -16,11 +16,10 @@ provoking a 2.0 failure under Linux.
 NUM_THREADS = 20
 FILES_PER_THREAD = 50
 
-import _thread as thread # If this fails, we can't test this module
-import threading
 import tempfile
 
-from test.support import threading_setup, threading_cleanup, run_unittest
+from test.support import threading_setup, threading_cleanup, run_unittest, import_module
+threading = import_module('threading')
 import unittest
 import io
 from traceback import print_exc
diff --git a/Lib/test/test_threading.py b/Lib/test/test_threading.py
index ef718ec..5ebc482 100644
--- a/Lib/test/test_threading.py
+++ b/Lib/test/test_threading.py
@@ -5,8 +5,8 @@ from test.support import verbose
 import random
 import re
 import sys
-import threading
-import _thread
+_thread = test.support.import_module('_thread')
+threading = test.support.import_module('threading')
 import time
 import unittest
 import weakref
diff --git a/Lib/test/test_threading_local.py b/Lib/test/test_threading_local.py
index cd2bed9..d676196 100644
--- a/Lib/test/test_threading_local.py
+++ b/Lib/test/test_threading_local.py
@@ -1,7 +1,7 @@
 import unittest
 from doctest import DocTestSuite
 from test import support
-import threading
+threading = support.import_module('threading')
 import weakref
 import gc
 
diff --git a/Lib/test/test_threadsignals.py b/Lib/test/test_threadsignals.py
index 7959e91..cb485fe 100644
--- a/Lib/test/test_threadsignals.py
+++ b/Lib/test/test_threadsignals.py
@@ -1,11 +1,11 @@
 """PyUnit testing that threads honor our signal semantics"""
 
 import unittest
-import _thread as thread
 import signal
 import os
 import sys
-from test.support import run_unittest
+from test.support import run_unittest, import_module
+thread = import_module('_thread')
 
 if sys.platform[:3] in ('win', 'os2') or sys.platform=='riscos':
     raise unittest.SkipTest("Can't test signal on %s" % sys.platform)
diff --git a/Lib/test/test_urllib2_localnet.py b/Lib/test/test_urllib2_localnet.py
index 5ffd779..4489356 100644
--- a/Lib/test/test_urllib2_localnet.py
+++ b/Lib/test/test_urllib2_localnet.py
@@ -1,13 +1,13 @@
 #!/usr/bin/env python3
 
 import email
-import threading
 import urllib.parse
 import urllib.request
 import http.server
 import unittest
 import hashlib
 from test import support
+threading = support.import_module('threading')
 
 # Loopback http server infrastructure
 
diff --git a/Lib/test/test_xmlrpc.py b/Lib/test/test_xmlrpc.py
index 3bc88eb..e082a2b 100644
--- a/Lib/test/test_xmlrpc.py
+++ b/Lib/test/test_xmlrpc.py
@@ -5,7 +5,6 @@ import time
 import unittest
 import xmlrpc.client as xmlrpclib
 import xmlrpc.server
-import threading
 import http.client
 import socket
 import os
@@ -14,6 +13,11 @@ import io
 import contextlib
 from test import support
 
+try:
+    import threading
+except ImportError:
+    threading = None
+
 alist = [{'astring': 'foo@bar.baz.spam',
           'afloat': 7283.43,
           'anint': 2**20,
@@ -399,10 +403,12 @@ def make_request_and_skipIf(condition, reason):
         return make_request_and_skip
     return decorator
 
+@unittest.skipUnless(threading, 'Threading required for this test.')
 class BaseServerTestCase(unittest.TestCase):
     requestHandler = None
     request_count = 1
     threadFunc = staticmethod(http_server)
+
     def setUp(self):
         # enable traceback reporting
         xmlrpc.server.SimpleXMLRPCServer._send_traceback_header = True
@@ -678,6 +684,9 @@ class GzipServerTestCase(BaseServerTestCase):
                 connection.putheader("Content-Encoding", "gzip")
             return xmlrpclib.Transport.send_content(self, connection, body)
 
+    def setUp(self):
+        BaseServerTestCase.setUp(self)
+
     def test_gzip_request(self):
         t = self.Transport()
         t.encode_threshold = None
@@ -714,13 +723,23 @@ class GzipServerTestCase(BaseServerTestCase):
 
 #Test special attributes of the ServerProxy object
 class ServerProxyTestCase(unittest.TestCase):
+    def setUp(self):
+        unittest.TestCase.setUp(self)
+        if threading:
+            self.url = URL
+        else:
+            # Without threading, http_server() and http_multi_server() will not
+            # be executed and URL is still equal to None. 'http://' is a just
+            # enough to choose the scheme (HTTP)
+            self.url = 'http://'
+
     def test_close(self):
-        p = xmlrpclib.ServerProxy(URL)
+        p = xmlrpclib.ServerProxy(self.url)
         self.assertEqual(p('close')(), None)
 
     def test_transport(self):
         t = xmlrpclib.Transport()
-        p = xmlrpclib.ServerProxy(URL, transport=t)
+        p = xmlrpclib.ServerProxy(self.url, transport=t)
         self.assertEqual(p('transport'), t)
 
 # This is a contrived way to make a failure occur on the server side
@@ -733,6 +752,7 @@ class FailingMessageClass(http.client.HTTPMessage):
         return super().get(key, failobj)
 
 
+@unittest.skipUnless(threading, 'Threading required for this test.')
 class FailingServerTestCase(unittest.TestCase):
     def setUp(self):
         self.evt = threading.Event()